Effect of water vapor and hydrocarbons in removing NOx by usingnon-thermal plasma and catalyst

摘要

The effect of water vapor and hydrocarbons in removing NO_x was experimentally studied by combining nonthermal plasma withvarious type of catalyst. Catalysts tested in this paper werecopper-coated zeolite, and conventional 3-way catalysts. The combinedprocess of the catalyst and the nonthermal plasma was examinedexperimentally. Water vapor from 0 to 15% was added in the flue gas tosimulate real exhaust gas conditions and compared to dry conditions.With 10% of water vapor, an NO removal rate of about 70% was obtainedwith a Na-ZSM-5 catalyst at 200-500° C where plasma discharge was notapplied. Nonthermal plasma improves NO_x removal rate with 10%water vapor and Na-ZSM-5 at any temperature. Such a high removal ratedid not resulted solely in chemical reaction but also absorption by thecatalyst. Nonthermal plasma degrades NO_x removal rate withCu-ZSM-5 with a gas temperature of 300° C or above. With a gastemperature of 100° C, the nonthermal plasma process is enhanced bythe combination of nonthermal plasma and any type of catalyst. Thecatalysts investigated in this paper do not work at such lowtemperature. Absorption characteristics were also investigated and onlyNa-ZSM-5 showed remarkable absorption characteristics